The midnight sun occurs in summer months mostly north of the Arctic Circle and south of the Antarctic Circle where the sun remains visible at midnight.
At mid summer there’s daylight all day due to almost no sunset in the high north of Norway, instead the sun stays below horizon at mid winter, often referred to as “Polar Night”. At the North Cape, the midnight sun is visible, if it is not overcast, from 14 May to 29 July. The visibility season narows geographical towards the Polar Circle. The sun stays over the horizon at midnight from about 20 May to 26 July, viewed from Birtavarre.